Amazingly, the whole redesign took less than a year, from start to finish.

In fact, the core work took place over a two-week period, in secret, and far away from eBay's headquarters in San Jose, Calif.

The project was led by Jack Abraham, the founder of Milo, a local-shopping startup he sold to eBay in 2010. Abraham and eBay haven't spoken much about the development of the new homepage—called the "Feed."

In February 2012, eBay CEO John Donahoe and Abraham sat down for an agenda-free conversation about how eBay could innovate. Abraham pitched the idea for the Feed. Donahoe gave him the go-ahead.

The next day, Abraham flew a team of six people to Australia to develop it. He expressed admiration for Expensify's practice of taking its team abroad for a month, which lets team members bond while keeping them highly productive. With an ocean between the team and headquarters, they were able to avoid politics and just ship code.

The group continued to work on the redesign after proving out the concept. In October, the redesign rolled out in a test to 10 percent of eBay's users, then progressively expanded; today it became available to all of eBay's users.

With the project complete, Abraham is leaving eBay while remaining an advisor to Donahoe.

Now the Feed project is led by Tom Pinckney, a New York-based engineering director who came to eBay through its acquisition of Hunch.